1. Field of the Invention
The present invention is directed to a structure of a capsule for a rapidly expanding metallic mixture, capable of easily providing high temperatures required to initiate an oxidation reaction of the metallic mixture, due to high voltage applied from a high voltage generator.
2. Description of the Prior Art
The rapidly expanding metallic mixture used in the present invention was invented by the present inventors, and was patented by Korean Intellectual Property Office (Korean Patent No. 10-0213577).
The rapidly expanding metallic mixture disclosed in Korean Patent No. 10-0213577 can be defined as follows.
In a mixture of a metal salt and a metal powder subjected to a high temperature of 700xc2x0 C. or more (about 1,500xc2x0 C.) (as such, temperature to be applied varies with types and mixing ratios of metal salt and metal powder), while the metal salt allows the metal powder to be oxidized, oxidation heat of ultrahigh temperatures (3,000-30,000xc2x0 C.) is instantaneously generated. When such a reaction is induced in a closed space, superhigh pressure of vaporization expansion (40,000-60,000 kg/cm2) is generated due to the oxidation heat. Immediately after such expansion, volume shrinkage occurs. The present inventors confirmed the reaction results through repeated experiments involving the above reaction. In particular, the above reaction readily proceeds upon mixing of the metal salt and the light metal powder.
In this regard, when a mixture of ferric nitrate (Fe(NO3)3) and manganese (Mn) powder is subjected to a thermal shock of about 1500xc2x0 C., the following reaction occurs.
2Fe(NO3)3+12Mnxe2x86x922FeO+4Mn3O4+3N2
In the above reaction, oxidation heat of 10,000xc2x0 C. or higher is generated, by which iron (Fe) and manganese oxide (Mn3O4) products are vaporized and rapidly expanded. During vaporization and rapid expansion, a reverse reaction of the above reaction does not occur. When the volume becomes larger due to rapid expansion, internal temperature decreases. As such, iron (Fe) and manganese oxide (Mn3O4) are changed in state from gas to solid, and expansion pressure disappears instantaneously. According to a Charles"" Law related to volume and temperature or a theory of adiabatic expansion, a phenomenon of temperature decrease due to rapid expansion can be explained.
Thus, the rapidly expanding metallic mixture is defined as a mixture comprising the metal salt as an oxidizing agent and the metal powder oxidized at high temperatures of 700xc2x0 C. or more (about 1,500xc2x0 C.) by the metal salt.
As such, the generated oxidation heat, which is ultrahigh temperature heat of 3,000-30,000xc2x0 C., vaporization expands the product after oxidation, thus creating superhigh pressure of 40,000-60,000 kg/cm2 in the closed space.
Such oxidation reaction and rapid expansion occurring only at such high temperature conditions suggest industrial applicability of the metallic mixture. Hence, the metallic mixture can be substituted for conventionally used dynamite, thus being suitable for use in blasting rock masses in construction works. Compared to dynamite, the metallic mixture of the present invention is much higher in expansion force and shorter in a time period required for oxidation. In addition, immediately after the condition of high temperature is removed by rapid expansion, the vaporization expanded product is changed to the solid state and thus expansion reaction stops. Therefore, there is no scattering of the broken fragments, and explosive sound during rapid expansion is remarkably reduced. The reason why conventional gunpowder and the inventive metallic mixture have different effects is that conventional gunpowder employs oxidation and vaporization of organic materials, whereas the rapidly expanding metallic mixture of the present invention uses oxidation and vaporization of metals. In such conventional gunpowder, even though the internal temperature is decreased after rapid expansion, gas products are not changed again to the solid state and diffused in the gaseous state. So, conventional gunpowder suffers from the disadvantages in terms of scattering many fragments, and creating a loud explosive sound and large explosive vibration. In addition, since typically used gunpowder may be fired even at relatively low temperatures of about 250xc2x0 C., it should be carefully handled during transport and storage. However, the inventive metallic mixture is advantageous in light of no possibility of accidental explosion during storage and handling of the materials due to the oxidation reaction being generated only at high temperatures not easily applied.
As the above metal salt, metal nitrates are most preferable, but the invention is not limited thereto. In addition, the metal salts are exemplified by metal oxides, metal hydroxides, metal carbonates, metal sulfates and metal perchlorates. Such a metal salt may be used alone or in combinations thereof. In particular, the metal nitrates may be further added with at least one metal salt selected from among metal oxides, metal hydroxides, metal sulfates, and metal perchlorates, to control the temperature required for initiation of oxidation and the time period required for oxidation.
The metal nitrates include, but are not limited to, ferric nitrate (Fe(NO3)3), copper nitrate (Cu(NO3)2), barium nitrate (Ba(NO3)2), manganese nitrate (Mn(NO3)4), magnesium nitrate (Mg(NO3)2), potassium nitrate (KNO3), sodium nitrate (NaNO3), calcium nitrate (Ca(NO3)2), and combinations thereof.
The metal oxides include, but are not limited to, manganese oxide (Mn3O4), calcium oxide (CaO), titanium oxide (TiO2), manganese dioxide (MnO2), chromium oxide (Cr2O3), ferric oxide (Fe2O3), triiron tetroxide (Fe3O4), nickel oxide (NiO), copper oxide (CuO), zinc oxide (ZnO), potassium oxide (K2O), sodium oxide (Na2O), dinickel trioxide (Ni2O3), lead oxide (PbO), lithium oxide (Li2O), barium oxide (BaO), strontium oxide (SrO), boron oxide (B2O3), and combinations thereof.
The metal hydroxides include, but are not limited to, lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2), barium hydroxide (Ba(OH)2), strontium hydroxide (Sr(OH)2), zinc hydroxide (Zn(OH)2), ferric hydroxide (Fe(OH)3), copper hydroxide (Cu(OH)2), nickel hydroxide (Ni(OH)2), manganese hydroxide (Mn(OH)3), chromium hydroxide (Cr(OH)3), magnesium hydroxide (MgOH), and combinations thereof.
The metal carbonates include, but are not limited to, lithium carbonate (Li2CO3), potassium carbonate (K2CO3), sodium carbonate (Na2CO3), calcium carbonate (CaCO3), barium carbonate (BaCO3), strontium carbonate (SrCO3), zinc carbonate (ZnCO3), ferrous carbonate (FeCO3), copper carbonate (CUCO3), nickel carbonate (NiCO3), manganese carbonate (MnCO3), chromium carbonate (CrCO3), magnesium carbonate (MgCO3), and combinations thereof.
The metal sulfates include, but are not limited to, potassium sulfate (K2SO4), lithium sulfate (Li2SO4), sodium sulfate (Na2SO4), calcium sulfate (CaSO4), barium sulfate (BaSO4), strontium sulfate (SrSO4), zinc sulfate (ZnSO4), ferrous sulfate (FeSO4), copper sulfate (CuSO4), nickel sulfate (NiSO4), aluminum sulfate (Al2(SO4)3), manganese sulfate (MnSO4), magnesium sulfate (MgSO4), chromium sulfate (CrSO4), and combinations thereof.
The metal perchlorates include, but are not limited to, potassium perchlorate (KClO4), lithium perchlorate (LiClO4), sodium perchlorate (NaClO4), calcium perchlorate (Ca(ClO4)2), barium perchlorate (Ba(ClO4)2), zinc perchlorate (Zn(ClO4)2), ferrous perchlorate (Fe(ClO4)3), manganese perchlorate (Mn(ClO4)2), magnesium perchloratee (Mg(ClO4)2), and combinations thereof.
The metal powder is preferably selected from the group consisting of aluminum (Al) powder, sodium (Na) powder, potassium (K) powder, lithium (Li) powder, magnesium (Mg) powder, calcium (Ca) powder, manganese (Mn) powder, barium (Ba) powder, chromium (Cr) powder, silicon (Si) powder, and combinations thereof.
A mixing ratio of the metal salt and the metal powder is defined as a ratio of oxygen amounts generated from the metal salts and oxygen amounts required for oxidization of metal powders, which is a ratio of molecular weights calculated from chemical formulas. The time period required for oxidation of the metal powder in each capsule is a moment in the range of 1/2,000 to 1/100 sec.
The composition, function and preparation process of the rapidly expanding metallic mixture is specifically disclosed in Korean Pat. No. 10-0213577. In the present invention, which is to allow industrial applicability of the rapidly expanding metallic mixture disclosed in Korean Pat. No. 10-0213577, the metallic mixture itself is not further described.
The condition of high temperature required to trigger the oxidation reaction may be provided by a variety of methods. Particularly, the present invention provides a capsule structure for a rapidly expanding metallic mixture, in which high voltage arc-discharge heat can be used as a heat source. In the case of applying arc discharge, temperatures reaching several thousands of degrees (xc2x0 C.) may be easily generated.
The present invention concerns a capsule structure for a rapidly expanding metallic mixture, capable of applying a high temperature required for triggering of oxidation reaction, to the rapidly expanding metallic mixture.
Therefore, it is an object of the present invention to provide a capsule for a rapidly expanding metallic mixture, which has a structure capable of easily providing the triggering temperature required for initiation of an oxidation reaction of the metallic mixture.
Another object of the present invention is to provide a capsule for a rapidly expanding metallic mixture, which has a structure capable of easily and effectively triggering an oxidation reaction of the metallic mixture, even in the case of a long capsule, the structure also inducing an effective arc discharge as well as generating sparks at several points even with the use of low voltage.
A further object of the present invention is to provide a capsule for a rapidly expanding metallic mixture, which has a structure capable of minimizing the diameter of the capsule installation hole, drilled in a target material to be blasted, and allowing an easy insertion of the capsule into the capsule installation hole.
In order to accomplish the above objects, the present invention provides a structure of the capsule for a rapidly expanding metallic mixture, comprising: an outer casing made of an insulating material; a rapidly expanding mixture contained in the outer casing; a pair of main trigger electrodes for inducing arc discharge, the main trigger electrodes being embedded in the metallic mixture; and a pair of power supply rods electrically connected to the main trigger electrodes, respectively, so as to apply high voltage from an external high voltage generator to the main trigger electrodes.
When using a long capsule, the capsule structure preferably comprises one or more trigger electrode support rods arranged between the main trigger electrodes, such that the trigger electrode support rods are linearly aligned with the main trigger electrodes, with an additional trigger electrode provided at each end of the trigger electrode support rods. In such a case, it is possible to effectively induce arc discharge at several points even with the use of low voltage, as well as preferably reducing the length of resistance wires. In the capsule structure with the trigger electrode support rods, an insulating support base is provided in the metallic mixture inside the outer casing, and one or more rod supports respectively extend from the insulating support base to the trigger electrode support rods, thus supporting the trigger electrode support rods, such that the trigger electrode support rods are linearly aligned with the main trigger electrodes.
In the capsule structure, a resistance wire is connected between adjacent trigger electrodes so as to induce arc discharge between the trigger electrodes via rapid heating, melting and evaporation when high voltage is applied to the trigger electrodes. Due to such resistance wires, it is easy to induce the arc discharge between the trigger electrodes.
In addition, it is preferable to add an electrolyte to the metallic mixture and arrange the trigger electrodes at intervals of 1-100 mm, and, in such a case, the arc discharge is readily induced between the trigger electrodes even without a resistance wire.
The power supply rods may lead outward from both ends of the outer casing, respectively. This structure simplifies the internal construction of the capsule, but is problematic in that it complicates the manipulation of the capsule, as well as requiring an enlargement in the diameter of the capsule installation hole, formed on the target material to be blasted.
Alternatively, all the power supply rods may lead outward from one end of the outer casing. This structure allows easy manipulation of the capsule, as well as allowing a reduction in the diameter of the capsule installation hole formed in the target material to be blasted, but is problematic in that it complicates the internal construction of the capsule.
The rapidly expanding metallic mixture, contained in the capsule, comprises a mixture of a metal powder with a metal salt responsible for oxidation of the metal powder at high temperatures of 700xc2x0 C. or more (about 1,500xc2x0 C.).
The metal salt of the mixture is selected from among metal nitrates, metal oxides, metal hydroxides, metal carbonates, metal sulfates, metal perchlorates, and combinations thereof.
The metal powder of the mixture is selected from among aluminum (Al), sodium (Na), potassium (K), lithium (Li), magnesium (Mg), calcium (Ca), manganese (Mn), barium (Ba), chromium (Cr), silicon (Si), and combinations thereof.
The rapidly expanding metallic mixture is further added with a water repellent such as oil or an inorganic preservative, to prevent oxidation of the metal powder during storage. In addition, particles of the rapidly expanding metallic mixture are coated with a resin and formed to the volume of 0.1-100 mm3, and then introduced into the outer casing, thereby preventing oxidation of the metal powder.